Complaint

My name is Molefe Tsotetsi with cell number *** I own Hyundai i20. 1.2 motion,I have a complaint against Hyundai Germiston. On the 12 May 2022, I took my vehicle for service 60000 km and ever since then my vehicle started consuming too much fuel and it t had lack of power, I took my car back where the vehicle service was carried out two weeks after and I had to pay R1758.90 as I told my vehicle had an oxygen sensor problem and I was told it was fixed, I've been to Hyundai Germiston more than 5 times with the very same problem fuel consumption and lack of power and each and every time I was there I had to pay out of my own pocket for a problem that my vehicle never had before, before I took it for service, as am writing this complaint my vehicle is at Hyundai Germiston, it has been there for 2 weeks they say I must pay R13500.00 for the very same problem, am struggling to get help, for a problem that my vehicle had never had before I took it to Hyundai Germiston the service manager Roger drove the vehicle and told me that it had no problem until I insisted that they should diagnosed the vehicle infront of me,a problem was found the very same problem of high fuel consumption and lack of power the very same problem I have been to their dealership for more than 5 times, they are very unprofessional and I am being ****** am very said about their poor service...I just want my car to be fixed that's all please assist.